This invention relates to the conversion of cyclopentadienyl compounds to titanium organometallic complexes by treatment with a dialkoxy titanium dihalide.
U.S. Pat. Nos. 5,491,246 and 5,504,223 describe the treatment of Me4C5SiMe2Ntxe2x80x94Bu(Li2) with titanium tetraisopropoxide to provide Me4C5SiMe2Ntxe2x80x94BuTi(OiPr)2.
It is known to convert certain cyclopentadienyl amines to titanium organometallic complexes including titanium bisalkoxide or dichloride complexes by treatment with titanium tetraisopropoxide and silicon tetrachloride.
No known prior art discloses the use of a dialkoxy titanium dihalide to convert a cyclopentadienyl compound to an organometallic complex that includes a titanium bisalkoxy or dichloride moiety.
In this specification, the following expressions have the meanings set forth hereinafter:
(1) Cyclopentadienyl means any substituted or unsubstituted cyclopentadienyl compound group or moiety, including but not limited to any alkylcyclopentadienyl, any indenyl, or alkyl indenyl group, preferably a C1 to C5 alkyl group.
(2) Alkoxide means any radical or group having the formula xe2x80x94OR, wherein R is an alkyl group.
(3) Cyclopentadienyl silyl amine means a compound of Formula 
in which Z is a cyclopentadienyl group or moiety and each of R1, R2 and R3 is independently, the same or a different alkyl group, preferably a C1 to C10 alkyl group.
(4) Constrained Geometry means that the metal atom in the metal coordination complex and also in the catalyst resulting therefrom is forced to greater exposure of the active catalyst site because of a specific ring structure of a ligand group including the metal atom, wherein the metal is both bonded to an adjacent covalent moiety and held in association with the delocalized xcfx80-bonded cyclopentadienyl group through an xcex75 or other xcfx80-bonding interaction. It is understood that each respective bond between the metal atom and the constituent atoms of the xcfx80-bonded moiety need not be equivalent, that is, the metal may be symmetrically or unsymmetrically xcfx80-bound thereto.
In general, the invention may comprise a process wherein a ligand of a titanium organometallic complex is reacted with dihalo titanium dialkoxide to provide a reaction mixture including a titanium bisalkoxide derivative of said ligand. In an advantageous practice of the invention, the ligand utilized is of a titanium organometallic complex having constrained geometry. The bisalkoxide may be converted to the corresponding titanium dichloride by treatment with a chlorinating agent, e.g., SiCl4, AlCl3 or BCl3.
The generic scope of the invention includes any ligand that forms a titanium bisalkoxide when treated with a dihalotitanium dialkoxide of formula Cl2Ti(OR)2.
The invention also includes a process which comprises reacting, in a non-interfering solvent, a ligand of a titanium organometallic complex with X2Ti(OR)2, wherein X is a halogen and R is a C1 to C5 alkyl group, wherein a reaction mixture comprising a solution in said medium of a titanium bisalkoxide derivative of said ligand is produced, wherein said ligand is a cyclopentadienyl silyl amine, or wherein said ligand is a ligand of a constrained geometry complex.
The invention may also include the process for producing a titanium bisalkoxide complex which comprises:
(i) treating a lithiated cyclopentadienyl silyl amine with Cl2Ti(OR)2,
wherein R is a C1 to C5 alkyl group,
wherein a first reaction mixture is produced, and
wherein said first reaction mixture contains a titanium bisalkoxide complex and lithium chloride, and
(ii) removing said lithium chloride from said first reaction mixture
wherein a mother liquor containing a solution of said titanium bisalkoxide complex is produced.
In general, a compound comprising a cyclopentadienyl moiety, typically a silyl amine, is deprotonated with an alkali metal, preferably a lithium alkyl, in a non-interfering medium, e.g., a mixture of hexane and ethyl ether, at a temperature of from about xe2x88x9220xc2x0 C. to room temperature. The deprotonated cyclopentadienyl compound is treated with Cl2Ti(OR)2 at an initial low temperature, e.g., xe2x88x9220 to xe2x88x9235xc2x0 C., which is raised to room temperature over an appropriate time period. The intermediate bis(alkoxy titanate) complex that forms is treated with silicon tetrachloride, boron trichloride, or phosphorous trichloride, preferably at xe2x88x9220 to xe2x88x9235xc2x0 C., for conversion to the metallocene dichloride. The dichloride may be converted to a metallocene by treatment with diene in the reaction mixture in which it is produced. Optionally, the dichloride may be separated from the reaction mixture prior to conversion. The metallocene complex product is alkali metal free.